Culture media desing for screening fo biogenic amine producin lactic acid bacteria

SAVINO MJ; ARENA ME; MANCA DE NADRA MC

BIOCELL

INCA

Lugar: Mendoza; Año: 2007 vol. 31 p. 301 - 301

0327-9545

Biogenic amines (BA), organic bases, generated by microorgan­isms could spoilage fermented foods. BA are measured by com­plex and expensiye techniques, for this reason is important to set a reliable method for detection oflactic acid bacteria (LAB) that pro­duce BA. The objectiye was fo design a culture media that allows a qualitatiye detection of LAB isolated from apples that produce tyramine (tyra) from tyrosine (tyr). Two culture media were as­sayed: Media 1 (MI) in gil: peptone, 5; yeast, 3; glucose (glc) 0.5; tomato juice, 2%y/y; bromocresol green, 0.04%; Media 2 (M2): peptone and yeast were not modified; glc, l gil; tomato juice 5%yl Y, bromocresol purple, 0.04%. The cultures medja were added with tyr 19/1, pyridoxal phosphate, 0.006 gil; two initial pH yalues were tested: 4.5 and 5.2. Tyra was quantified by HPLC. In the first 5 days incubation pH indicators showed an acidification. The pro­duction of BA is indicated by media alkalinization, changing the colour media (MI). This fact was obseryed after 5 days incubation for strains 44, 66, 68 of L. plantarum and 37, 72 of L. brevis, at both pH. In M2 persisted yellow colour during the lO days incuba­tion. Tyr decarboxylase actiyity was corroborated for the strains 44 and 72 of L. plantarum. The initial pH did not modify the results. The design MI appears to be a simple method to detect LAB that produce tyra.